The delivery of drugs into systemic circulation via skin has generated much attention during the last decade. Transdermal therapeutic systems propound controlled release of active ingredients through the skin and into the systemic circulation in a predictive manner. Drugs administered through these systems escape first-pass metabolism and maintain a steady state scenario similar to a continuous intravenous infusion for up to several days. However, the excellent impervious nature of the skin offers the greatest challenge for successful delivery of drug molecules by utilizing the concepts of iontophoresis. The present review deals with the principles and the recent innovations in the field of iontophoretic drug delivery system together with factors affecting the system. This delivery system utilizes electric current as a driving force for permeation of ionic and non-ionic medications. The rationale behind using this technique is to reversibly alter the barrier properties of skin, which could possibly improve the penetration of drugs such as proteins, peptides and other macromolecules to increase the systemic delivery of high molecular weight compounds with controlled input kinetics and minimum inter-subject variability. Although iontophoresis seems to be an ideal candidate to overcome the limitations associated with the delivery of ionic drugs, further extrapolation of this technique is imperative for translational utility and mass human application.

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Nanotechnology is expected to revolutionize existing drug delivery. Many nanostructured systems have been employed for drug delivery and yielded some promising results. Solid lipid nanoparticles (SLN) have been looked at as a potential drug carrier system since last two decades. SLN do not show biotoxicity as they are prepared from physiological lipids. SLN are especially useful in drug delivery as they can enhance the absorption of drugs and improves the bioavailability of both hydrophilic and lipophilic drugs. This paper presents an overview about the various classes of SLN, comparison with available drug carrier systems, different ways of production, in vivo fate and biodistribution and various applications of SLN. Besides, aspects of stability, hurdles and strategies for SLN manufacturing with potential of clinical translation are also discussed.

Solid dispersion has emerged as a method of choice and has been extensively investigated to ascertain the in vivo improved performance of many drug formulations. It generally involves dispersion of drug in amorphous particles (clusters) or in crystalline particles. Comparatively, in the last decade, amorphous drug-polymer solid dispersion has evolved into a platform technology for delivering poorly water-soluble small molecules. However, the success of this technique in the pharmaceutical industry mainly relies on different drug-polymer attributes like physico-chemical stability, bioavailability and manufacturability. The present review showcases the efficacy of amorphous solid dispersion technique in the research and evolution of different drug formulations particularly for those with poor water soluble properties. Apart from the numerous mechanisms of action involved, a comprehensive summary of different key parameters required for the solubility enhancement and their translational efficacy to clinics is also emphasized.

The solubility of drugs is one of the most challenging aspects in developing formulations for novel drug discovery. Myriad of approaches have been developed and tested to overcome the associated intricacies involved with poor water soluble drugs. Out of the available technologies, solid dispersion (SD) method that significantly enhances the solubility and bioavailability by reducing particle size to a micro-molecular level is often viewed as a promising strategy. Although conceptual basis of manufacturing processes involved in SD method have been reported, formulation characteristics addressing solubility issues remains yet elusive. The current review portray the historical milestones, classification, probable mechanisms for enhancement of solubility, manufacturing processes at commercial level along with pioneer breakthroughs in field that enunciates the versatile pharmaceutical application for categories including anti-cancer and anti-retroviral drugs. Besides, our article also highlights the translational implications of drug development by SD method hitherto unreported.